Researchers find that the most common explanation for cognitive symptoms that resemble attention-deficit/hyperactivity disorder is substance abuse.
A new study appearing in the American Journal of Psychiatry is sure to set off debate about an already controversial topic: can older teens or adults develop attention-deficit/hyperactivity disorder (ADHD) out of the blue, or are their symptoms a sign of something else?
The restlessness and lack of concentration diagnosed among adults in recent years has been attributed to a late-onset variety of ADHD, compared with the classic form of the condition that is diagnosed between ages 5 and 12. But in this new study, researchers went back and reassessed 239 patients who had been diagnosed with late-onset ADHD based on reports from parents, teachers, or descriptions of their own symptoms. The average age of the subjects was 24.4 years, and their symptoms were compared to a baseline of just under 10 years old.
The researchers found that in 95% of the cases, there was another explanation for the symptoms, and ADHD could be excluded. The most common reason for sudden impairment? Substance abuse. But nearly all symptoms occurred in the context of a mood disorder, suggesting that the cognitive impairments may precede some other problem, such as depression or anxiety. One patient in the study had previously suffered an eating disorder. A another displayed signs of mania.
The authors didn’t hedge in their findings: “There was no evidence for adult-onset ADHD independent of a complex psychiatric history,” they wrote.
It’s not that patients who seek treatment for symptoms that resemble ADHD are not experiencing them, the authors say—it’s just that it might not be ADHD.
“More commonly, symptoms represent nonimpairing cognitive fluctuations, a comorbid disorder, or the cognitive effects of substance use,” they wrote. “False positive late-onset ADHD cases are common without careful assessment. Clinicians should carefully assess impairment, psychiatric history, and substance use before treating potential late-onset cases.”
Sibley MH, Rohde LA, Swanson JM, et al. Late-onset ADHD reconsidered with comprehensive repeated assessments between ages 10 and 25 [published online October 20, 2017]. Am J Psych. 2017; https://doi.org/10.1176/appi.ajp.2017.17030298